Ethisterone is primarily used in the field of medicine, particularly in hormonal therapies. It is a synthetic progestin, which means it mimics the effects of the natural hormone progesterone. This makes it valuable in treating various gynecological conditions. It is often prescribed to manage menstrual disorders, such as irregular periods or heavy bleeding, by regulating the menstrual cycle. Additionally, it has been used in the past to support pregnancy in cases of threatened miscarriage, although its use for this purpose has declined with the development of newer medications. Ethisterone also plays a role in hormone replacement therapy (HRT) for menopausal women, helping to alleviate symptoms associated with hormonal imbalances. Its applications are rooted in its ability to influence the reproductive system and maintain hormonal stability.